The present invention relates to an arrangement for delivering hydraulic fluid to at least one hydraulic actuator of a work vehicle for moving a work implement and/or steering the vehicle, comprising at least two pumps, which are adapted to be operatively driven by a power source and adapted to operatively drive said at least one hydraulic actuator via hydraulic fluid. The invention also relates to a corresponding method for delivering hydraulic fluid to at least one hydraulic actuator of a work vehicle.
The term “work vehicle” comprises different types of material handling vehicles like construction machines, such as a wheel loader, an articulated hauler, a backhoe loader, a motor grader and an excavator. Further terms frequently used for work vehicles are “earth-moving machinery” and “off-road work machines”. The work vehicles are for example utilized for construction and excavation work, in mines etc. The invention will be described below in a case in which it is applied in a wheel loader. This is to be regarded only as an example of a preferred application.
There is a desire to improve the working environment of a work vehicle operator with regard to noise, vibrations, shocks etc.
It is desirable to achieve an arrangement for delivering hydraulic fluid to at least one hydraulic actuator of a work vehicle, which creates conditions for a reduced noise and/or reduced vibrations during operation.
According to an aspect of the present invention, an arrangement is provided for delivering hydraulic fluid to at least one hydraulic actuator of a work vehicle for moving a work implement and/or steering the vehicle, comprising at least two pumps, which are adapted to be operatively driven by a power source and adapted to operatively drive said at least one hydraulic actuator via hydraulic fluid characterized in that a first pump is operated with a phase shift relative to a second pump.
In other words, the pumps are adapted so that a piston of a first pump is operated with a phase shift relative to a piston of a second pump. In this way, the pump pulsations in the hydraulic system will be reduced, which in turn leads to a reduced noise and/or vibrations during operation. Thus, the working environment for the vehicle operator is improved. A further advantage is that the hydraulic components in the system will be exposed to less stresses, which creates conditions for longer life.
According to one embodiment, the first pump is adapted to be operated with a constant phase shift relative to the second pump. This may be achieved in a cost-efficient way in that the pumps are arranged with said constant phase shift relative one another during assemblying. Thus, the positions of the pistons of the pumps are mechanically adjusted with regard to one another. In such a case, the operator of the vehicle can not interfere with the phase shift during operation. In other words, the first pump is manually rotated a predetermined angle relative to the second pump in order to accomplish said phase shift during assembly. The pumps are preferably operatively coupled to a common output from the power source.
Further preferred embodiments and advantages will be apparent from the following description and drawings.